JP2021056391A - Image forming apparatus - Google Patents

Abstract

To provide an image forming apparatus that can resolve inconvenience during calibration due to reference paper.SOLUTION: In a maintenance mode in which reference paper as paper for calibration of a paper information detection unit 80 is fed and conveyed, a control unit controls to reduce the quantity of heat given to the paper by a fixing unit 61 compared with a normal mode in which normal paper for image formation is fed and conveyed. Thus, even when paper vulnerable to heat is used as the reference paper, damage due to heat of the reference paper can be prevented.SELECTED DRAWING: Figure 1

Description

The present invention relates to an image forming apparatus having a function of detecting paper information such as paper thickness, glossiness and quality, and a control method thereof.

Conventionally, a sensor for detecting the type of paper is provided inside an image forming apparatus such as a printer, a copier, or a facsimile, and fixing conditions, transport conditions, transfer conditions, etc. are automatically set according to the type of paper detected by this sensor. There is an image forming device that can be set with.

For example, in Patent Document 1, in an image forming apparatus equipped with a paper type discriminating sensor for discriminating a paper type, print preparation such as fixing control and cartridge driving until the paper type is discriminated when the paper type automatic discriminating mode is specified is prepared. A technique for changing the operation based on the user's paper type usage history is described.

JP-A-2015-14695

By the way, when a sensor that detects the type of paper (generally called a media sensor) is installed in the transport path, the mounting position varies when the sensor is installed, and the sensor and the machine are distorted over time. Therefore, it is necessary to calibrate the characteristics of the sensor regularly while it is installed.

For calibration, synthetic paper (such as YUPO paper) different from the paper used for normal image formation (hereinafter referred to as normal paper) is used as the reference paper. This reference paper is a paper having more stable physical characteristics than ordinary paper. That is, the reference paper is a paper having a fixed thickness, glossiness, quality, etc. as compared with ordinary paper.

Here, the standard paper has water resistance and durability, but is weak against heat because it is made of a resin. Therefore, in the temperature band (around 200 [° C]) used in the fixing part of normal image formation, the reference paper shrinks and curls greatly, or the reference paper melts and damages the fixing part. There is a concern that it will occur.

An object of the present invention is to provide an image forming apparatus capable of eliminating inconveniences during calibration with a reference paper.

One aspect of the image forming apparatus of the present invention is
A transport unit that transports the paper stored in the paper feed tray along the transport path,
An image forming unit that forms an image on the paper conveyed by the conveying unit, and an image forming unit.
A fixing portion for fixing the image formed by the image forming portion on the previous term paper, and a fixing portion.
A paper information detection unit that is arranged in the transport path and detects information on the paper,
In the first mode in which the reference paper as the calibration paper of the paper information detection unit is fed and conveyed, the fixing unit causes the fixing unit to feed and convey the paper for image formation as compared with the second mode in which the paper for image formation is fed and conveyed. A control unit that controls the amount of heat given to the paper to a low level,
To be equipped.

According to the present invention, in the first mode in which the reference paper as the calibration paper of the paper information detection unit is fed and conveyed, compared with the second mode in which the image-forming paper is fed and conveyed. Since the amount of heat given to the paper is controlled to be low by the fixing part, it is possible to prevent damage due to heat of the reference paper even when heat-sensitive paper is used as the reference paper, and as a result, inconvenience when calibrating with the reference paper. Can be resolved.

It is a figure which shows schematic the whole structure of the image forming apparatus in this embodiment. It is a figure which shows the main part of the control system of the image forming apparatus in this embodiment. It is a flowchart which shows the processing procedure of maintenance mode.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

<1> Overall Configuration of Image Forming Device FIG. 1 is a diagram schematically showing an overall configuration of an image forming apparatus according to an embodiment of the present invention, and FIG. 2 shows a main part of a control system of the device. It is a figure.

The image forming apparatus 1 shown in FIGS. 1 and 2 is an intermediate transfer type color image forming apparatus using an electrophotographic process technique. That is, the image forming apparatus 1 transfers (primary transfer) the C (cyan), M (magenta), Y (yellow), and K (black) color toner images formed on the photoconductor to the intermediate transfer body. An image is formed by superimposing toner images of four colors on an intermediate transfer body and then transferring (secondary transfer) to paper.

Further, the image forming apparatus 1 employs a tandem method in which photoconductors corresponding to the four colors of CMYK are arranged in series in the traveling direction of the intermediate transfer body, and the toner images of each color are sequentially transferred to the intermediate transfer body in a single procedure. Has been done.

As shown in FIGS. 1 and 2, the image forming apparatus 1 includes an image reading unit 10, an operation display unit 20, an image processing unit 30, an image forming unit 40, a conveying unit 50, a fixing device 60, a paper information detecting unit 80, and a control. The unit 100 is provided.

The control unit 100 includes a CPU (Central Processing Unit) 101, a ROM (Read Only Memory) 102, a RAM (Random Access Memory) 103, and the like. The CPU 101 reads a program according to the processing content from the ROM 102, develops it in the RAM 103, and centrally controls the operation of each block of the image forming apparatus 1 in cooperation with the expanded program. At this time, various data such as a LUT (Look Up Table) stored in the storage unit 72 are referred to. The storage unit 72 is composed of, for example, a non-volatile semiconductor memory (so-called flash memory) or a hard disk drive.

The control unit 100 transmits and receives various data to and from an external device (for example, a personal computer) connected to a communication network such as a LAN (Local Area Network) or WAN (Wide Area Network) via the communication unit 71. Do. The control unit 100 receives, for example, image data transmitted from an external device, and forms an image on paper based on the image data (input image data). The communication unit 71 is composed of a communication control card such as a LAN card.

The image reading unit 10 includes an automatic document feeding device 11 called an ADF (Auto Document Feeder), a document image scanning device (scanner) 12, and the like.

The automatic document feeding device 11 conveys the document D placed on the document tray by the conveying mechanism and sends it out to the document image scanning device 12. The automatic document feeding device 11 can continuously read a large number of images (including both sides) of the documents D placed on the document tray at once.

The document image scanning device 12 optically scans the document D transported onto the contact glass from the automatic document feeding device 11 or the document D placed on the contact glass, and the reflected light from the document D is CCD ( Charge Coupled Device) An image is formed on the light receiving surface of the sensor 12a, and the original image is read. The image scanning unit 10 generates input image data based on the scanning result by the document image scanning device 12. The image processing unit 30 performs predetermined image processing on the input image data.

The operation display unit 20 is composed of, for example, a liquid crystal display (LCD) with a touch panel, and functions as a display unit 21 and an operation unit 22. The display unit 21 displays various operation screens and the operation status of each function according to the display control signal input from the control unit 100. The operation unit 22 includes various operation keys such as a numeric keypad and a start key, receives various input operations by the user, and outputs an operation signal to the control unit 100.

The image processing unit 30 includes a circuit that performs digital image processing according to initial settings or user settings on the input image data. For example, the image processing unit 30 performs gradation correction based on the gradation correction data (gradation correction table) under the control of the control unit 100. Further, the image processing unit 30 performs various correction processes such as color correction and shading correction, compression processing, and the like, in addition to gradation correction, on the input image data. The image forming unit 40 is controlled based on the image data subjected to these processes.

The image forming unit 40 is an image forming unit 41Y, 41M, 41C, 41K, and an intermediate transfer unit for forming an image with each colored toner of Y component, M component, C component, and K component based on the input image data. It is equipped with 42 and the like.

The image forming units 41Y, 41M, 41C, 41K for the Y component, the M component, the C component, and the K component have the same configuration. For convenience of illustration and description, common components are indicated by the same reference numerals, and when distinguishing them, they are indicated by adding Y, M, C or K to the reference numerals. In FIG. 1, the reference numerals are given only to the components of the image forming unit 41Y for the Y component, and the reference numerals are omitted for the other components of the image forming units 41M, 41C, and 41K.

The image forming unit 41 includes an exposure device 411, a developing device 412, a photoconductor drum 413, a charging device 414, a drum cleaning device 415, and the like.

The photoconductor drum 413 has, for example, an undercoat layer (UCL: Under Coat Layer), a charge generation layer (CGL: Charge Generation Layer), and a charge transport layer (CGL) on the peripheral surface of a conductive cylindrical body (aluminum tube) made of aluminum. It is a photoconductor having photoconductivity, which is formed by sequentially laminating CTL: Charge Transport Layer). The photoconductor drum 413 is, for example, a negatively charged organic photo-conductor (OPC).

The charging device 414 uniformly charges the surface of the photoconductor drum 413 having photoconductivity to a negative electrode property.

The exposure apparatus 411 is composed of, for example, a semiconductor laser, and irradiates the photoconductor drum 413 with a laser beam corresponding to an image of each color component. When positive charges are generated in the charge generation layer of the photoconductor drum 413 by irradiation with laser light and transported to the surface of the charge transport layer, the surface charge (negative charge) of the photoconductor drum 413 is neutralized. As a result, an electrostatic latent image of each color component is formed on the surface of the photoconductor drum 413 due to the potential difference from the surroundings.

The developing device 412 contains a developer for each color component (for example, a two-component developer composed of a toner having a small particle size and a magnetic material), and adheres the toner for each color component to the surface of the photoconductor drum 413. Visualizes the electrostatic latent image and forms a toner image.

The drum cleaning device 415 has a drum cleaning blade that is slidably contacted with the surface of the photoconductor drum 413. The transfer residual toner remaining on the surface of the photoconductor drum 413 after the primary transfer is scraped off and removed by the drum cleaning blade.

The intermediate transfer unit 42 (transfer device) includes an intermediate transfer belt 421 as an intermediate transfer body, a primary transfer roller 422, a secondary transfer roller 423, a drive roller 424, a driven roller 425, a belt cleaning device 426, and the like.

The intermediate transfer belt 421 is composed of an endless belt and is stretched on a drive roller 424 and a driven roller 425. The intermediate transfer belt 421 travels at a constant speed in the direction of arrow A due to the rotation of the drive roller 424. When the intermediate transfer belt 421 is pressed against the photoconductor drum 413 by the primary transfer roller 422, the toner images of each color are sequentially transferred to the intermediate transfer belt 421 so as to overlap each other (primary transfer). Then, when the intermediate transfer belt 421 is pressed against the paper S by the secondary transfer roller 423, the toner image transferred to the intermediate transfer belt 421 is transferred to the paper S (secondary transfer).

The belt cleaning device 426 has a belt cleaning blade that is slidably contacted with the surface of the intermediate transfer belt 421. The transfer residual toner remaining on the surface of the intermediate transfer belt 421 after the secondary transfer is scraped off and removed by the belt cleaning blade.

The fixing device 60 fixes the toner image on the paper S by heating and pressurizing the paper S having the toner image which is unfixed at the time of transfer from the intermediate transfer belt 421 at the nip portion (fixing step). The fixing device 60 is an air separation type fixing device including a fixing unit 61 and an air separating unit 62. The air separation unit 62 has a fan and separates the paper wound around the fixing unit 61 by air.

The transport unit 50 includes a paper feed unit 51, a transport mechanism 52, a paper discharge unit 53, and the like. The two paper feed tray units 51a to 51c constituting the paper feed unit 51 accommodate paper (standard paper, special paper) S identified based on the basis weight, size, and the like for each type.

The paper S housed in the paper feed tray units 51a to 51c is sent out one by one from the uppermost portion, and is conveyed to the image forming unit 40 by a conveying mechanism 52 provided with a plurality of conveying rollers such as a resist roller 52a. At this time, the resist portion on which the resist roller 52a is arranged corrects the inclination of the fed paper S and adjusts the transfer timing. Then, in the image forming unit 40, the toner image of the intermediate transfer belt 421 is transferred to one surface of the paper S, and the fixing step is performed in the fixing device 60. The paper S on which the toner image is fixed by the fixing step is discharged to the outside of the image forming apparatus 1 by the paper ejection unit 53 provided with the paper ejection roller 53a.

The paper information detection unit 80 is arranged in a transport path on the upstream side of the fixing device 60. The paper information detection unit 80 has, for example, a light emitting element and a light receiving element, and optically detects paper information such as the thickness, glossiness, and quality of the paper passing through the transport path.

The paper information obtained by the paper information detection unit 80 is input to the control unit 100. The control unit 100 can perform image forming processing according to the characteristics of the paper by adjusting, for example, the fixing temperature, the fixing nip pressure, the conveying speed, and the like based on the paper information.

<2> Calibration of the paper information detection unit The image forming apparatus 1 of the present embodiment has a maintenance mode for calibrating the paper information detection unit 80. The maintenance mode is executed by the control by the control unit 100. The maintenance mode is executed at the time of installing the image forming apparatus 1 or every few months as needed. In the maintenance mode, the reference paper is fed to the transport path and transported. As described above, the reference paper is a synthetic paper (such as YUPO paper) different from the normal paper used for image formation.

FIG. 3 is a flowchart showing a processing procedure of the maintenance mode according to the present embodiment. The image forming apparatus 1 starts the maintenance mode at the initial stage of installation or when an operation for starting the maintenance mode is performed by the user.

When the maintenance mode is started, the control unit 100 controls the heater of the fixing unit 61 to be turned off in step S1. Specifically, the heater of the heating roller (not shown) constituting the fixing portion 61 is controlled to be OFF.

In the following step S2, the control unit 100 turns on and controls the fixing separation fan constituting the air separation unit 62.

In the following step S3, the control unit 100 is changed so that the fixing and crimping force of the pressure roller (not shown) constituting the fixing unit 61 is weakened.

By executing steps S1, S2, and S3, the amount of heat given to the paper (reference paper) by the fixing unit 61 can be controlled to be low in the maintenance mode. That is, by performing steps S1 and S2, the temperature of the fixing portion 61 itself can be lowered, and by performing step S3, heat conduction to the paper (reference paper) via the rollers can be reduced.

In the following step S4, the control unit 100 determines whether or not the temperature of the fixing unit 61 is equal to or lower than a predetermined value (for example, 100 [° C]). Incidentally, the temperature of the fixing portion 61 is measured by a temperature sensor (not shown) provided in the fixing portion 61.

When the temperature of the fixing unit 61 becomes equal to or lower than a predetermined value, the control unit 100 proceeds to step S5 and starts feeding the reference paper from the paper feeding unit 51.

In the following step S6, the control unit 100 stops the reference paper at the position of the paper information detection unit 80, and in the subsequent step S7, the sensor calibration of the paper information detection unit 80 is executed.

In the following step S8, the control unit 100 conveys the reference paper from the paper information detection unit 80, and in step S9, the reference paper is ejected from the paper ejection unit 53. During the steps S8 to S9, the reference paper passes through the fixing portion 61, and the fixing portion 61 is controlled so that the amount of heat given to the reference paper is reduced by the processing of steps S1, S2, and S3. Therefore, the reference paper does not have to be damaged by heat by the fixing portion 61.

<3> Summary As described above, according to the present embodiment, when the control unit 100 is in the maintenance mode in which the reference paper as the paper for calibration of the paper information detection unit 80 is fed and conveyed, the image is displayed. By controlling the amount of heat given to the paper by the fixing unit 61 lower than in the normal mode in which the normal paper for forming is fed and conveyed, the heat of the reference paper is used even when the heat-sensitive paper is used as the reference paper. You will be able to prevent damage. As a result, it is possible to eliminate the inconvenience during calibration with the reference paper (a situation in which the reference paper is greatly shrunk and curled, or the reference paper is melted and the fixing portion 61 is damaged).

That is, the fixing unit 61 of the present embodiment fixes the toner on the paper by heat and pressure during normal image formation, but this is not necessary in the maintenance mode, so the heat and pressure are controlled to be small. , It is controlled so that heat is not transferred to the reference paper as much as possible.

Further, the control unit 100 controls so that the pressure-bonding force of the pressurizing roller on the paper at the fixing unit 61 in the maintenance mode is smaller than that in the normal mode (mode in which the normal paper is fed and conveyed at the time of image formation). (Step S3). As a result, the pressure can be weakened to prevent the amount of heat of the fixing portion 61 from being transferred to the reference paper as much as possible. The crimping force at this time is preferably the lowest crimping force capable of transporting the reference paper.

Further, in the maintenance mode, the control unit 100 lowers the temperature of the fixing unit 61 by turning on the fan of the air separating unit 62 that separates the paper wound around the fixing unit 61 by air (step S2). By doing so, it is possible to shorten the time for the temperature of the fixing portion 61 to drop to a desired temperature after the heating of the fixing portion 61 is stopped, and as a result, the waiting time until the sensor calibration is performed can be shortened.

It should be noted that the above-described embodiment is merely an example of the embodiment of the present invention, and the technical scope of the present invention should not be construed in a limited manner by these. That is, the present invention can be implemented in various forms without departing from its gist or its main features.

Generally, the image forming apparatus is provided with a temperature abnormality detecting function for detecting a temperature abnormality of the fixing portion 61. In this case, it is preferable to stop at least the abnormal low temperature detection function among the temperature abnormality detection functions in the maintenance mode. By doing so, it is possible to prevent the fixing portion 61 from being erroneously detected as abnormal by the temperature abnormality detection function in the maintenance mode.

Further, in addition to the above configuration, it is preferable that the image forming apparatus 1 has a storage unit that stores the execution history of the maintenance mode, and controls the power supply to the fixing unit 61 based on the execution history. With this configuration, for example, when the maintenance mode is not executed for a predetermined period or longer, the power supply to the fixing unit 61 can be stopped even if the power switch is operated. That is, normally, when the power is turned on, the warm-up mode is automatically entered, but if the maintenance mode is not executed in the maintenance mode execution history, the warm-up mode is not performed. By doing so, the maintenance mode can be started without warming up the fixing portion 61, so that the maintenance mode can be started without waiting for the temperature of the fixing portion 61 to drop, and the sensor can be started. The waiting time until calibration can be shortened. Further, since it is not necessary to turn on the fan of the air separation unit 62, the power consumption can be reduced.

Further, in the maintenance mode, the control unit 100 may switch the transport path of the reference paper to a path through which the paper information detection unit 80 passes but not through the fixing unit 61. For example, the reference paper may be conveyed to the position of the paper information detection unit 80 to perform sensor calibration, and then the reference paper may be conveyed so as to return to the original direction of the paper feeding unit 51. Further, another transport path that does not pass through the fixing portion 61 may be provided to discharge the paper. As a result, the amount of heat given to the reference paper by the fixing unit 61 in the maintenance mode is controlled to be zero.

Further, in the above-described embodiment, the image forming apparatus 1 having a maintenance mode for calibrating the paper information detection unit 80 has been described, but the present invention is not limited to this, and the image forming apparatus does not have a maintenance mode. Is also applicable. In short, when the control unit 100 is in the first mode in which the reference paper as the calibration paper of the paper information detection unit 80 is fed and conveyed, the second mode in which the normal paper for image formation is fed and conveyed. The amount of heat given to the paper by the fixing unit 61 may be controlled to be lower than in the case of. That is, the maintenance mode of the above-described embodiment can be read as the first mode in which the reference paper as the calibration paper of the paper information detection unit 80 is fed and conveyed.

1 Image forming device 10 Image reading unit 20 Operation display unit 21 Display unit 22 Operation unit 30 Image processing unit 40 Image forming unit 50 Transport unit 60 Fixing device 61 Fixing unit 62 Air separation unit 71 Communication unit 72 Storage unit 80 Paper information detection unit 100 Control unit 101 CPU
102 ROM
103 RAM

Claims (8)

A transport unit that transports the paper stored in the paper feed tray along the transport path,
An image forming unit that forms an image on the paper conveyed by the conveying unit, and an image forming unit.
A fixing portion for fixing the image formed by the image forming portion on the previous term paper, and a fixing portion.
A paper information detection unit that is arranged in the transport path and detects information on the paper,
In the first mode in which the reference paper as the calibration paper of the paper information detection unit is fed and conveyed, the fixing unit causes the fixing unit to feed and convey the paper for image formation as compared with the second mode in which the paper for image formation is fed and conveyed. A control unit that controls the amount of heat given to the paper to a low level,
An image forming apparatus comprising. The first mode includes a maintenance mode for calibrating the paper information detection unit.
The image forming apparatus according to claim 1. In the first mode, the control unit controls so that the pressure-bonding force of the pressure roller on the paper at the fixing unit is smaller than in the second mode.
Claim 1 or 2 Image forming apparatus. In the first mode, the control unit lowers the temperature of the fixing unit by turning on the fan of the air separating unit that separates the paper wound around the fixing unit by air.
The image forming apparatus according to claim 1 or 2. It has a temperature abnormality detection function that detects the temperature abnormality of the fixing part.
In the first mode, at least the abnormal low temperature detection function among the temperature abnormality detection functions is stopped.
The image forming apparatus according to claim 1 or 2. It has a storage unit that stores the execution history of the maintenance mode.
Control the power supply to the fixing unit based on the execution history.
The image forming apparatus according to claim 2. If the maintenance mode has not been performed for a predetermined period or longer, power is not supplied to the fixing unit in the previous period.
The image forming apparatus according to claim 6. In the first mode, the control unit switches the transport path of the reference paper to a path through which the paper information detection unit passes but does not pass through the fixing unit.
The image forming apparatus according to claim 1.

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